From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E56C3C77B7A for ; Wed, 24 May 2023 05:46:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233663AbjEXFqN convert rfc822-to-8bit (ORCPT ); Wed, 24 May 2023 01:46:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239493AbjEXFqM (ORCPT ); Wed, 24 May 2023 01:46:12 -0400 X-Greylist: delayed 896 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Tue, 23 May 2023 22:46:11 PDT Received: from smtprelay01.ispgateway.de (smtprelay01.ispgateway.de [80.67.31.39]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6CD8418B for ; Tue, 23 May 2023 22:46:11 -0700 (PDT) Received: from [89.1.81.74] (helo=karo-electronics.de) by smtprelay01.ispgateway.de with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1q1hK5-0003fA-OK; Wed, 24 May 2023 07:46:09 +0200 Date: Wed, 24 May 2023 07:46:07 +0200 From: Lothar =?UTF-8?B?V2HDn21hbm4=?= To: linux-arm-kernel@lists.infradead.org Cc: linux-pwm@vger.kernel.org, Lee Jones , NXP Linux Team , Fabio Estevam , Pengutronix Kernel Team , Shawn Guo , Thierry Reding Subject: Re: [PATCH V2] pwm: imx-tpm: fix kernel crash upon resume due to register access with clocks disabled Message-ID: <20230524074607.41ffc31b@karo-electronics.de> In-Reply-To: <20230524052714.3077-1-LW@KARO-electronics.de> References: <20230524052714.3077-1-LW@KARO-electronics.de> Organization: Ka-Ro electronics GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT X-Df-Sender: bHdAa2Fyby1lbGVjdHJvbmljcy5kb21haW5mYWN0b3J5LWt1bmRlLmRl Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org If the pwm-imx-tpm driver is being used e.g. for backlight, the pwm_imx_tpm_apply() function is being called before the device is resumed and the clocks are enabled, resulting in a data abort: echo +5 > /sys/class/rtc/rtc0/wakealarm;echo mem > /sys/power/state PM: suspend entry (deep) Filesystems sync: 0.006 seconds Freezing user space processes ... (elapsed 0.015 seconds) done. OOM killer disabled. Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done. Disabling non-boot CPUs ... psci: CPU1 killed (polled 0 ms) Enabling non-boot CPUs ... Detected VIPT I-cache on CPU1 cacheinfo: Unable to detect cache hierarchy for CPU 1 GICv3: CPU1: found redistributor 100 region 0:0x0000000048060000 CPU1: Booted secondary processor 0x0000000100 [0x412fd050] CPU1 is up Internal error: synchronous external abort: 0000000096000010 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 245 Comm: bash Not tainted 6.1.1-karo+g29549c7073bf #1 Hardware name: Ka-Ro electronics GmbH TX93-5210 (NXP i.MX93) module (DT) pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : pwm_imx_tpm_apply+0x12c/0x3f0 lr : pwm_imx_tpm_apply+0x104/0x3f0 sp : ffff80000a11b710 x29: ffff80000a11b710 x28: 0000000000000001 x27: 0000000000000000 x26: 0000000000000000 x25: 000000000007a12a x24: 0000000000008236 x23: 0000000000000000 x22: ffff00000309b5d0 x21: 0000000000000000 x20: ffff0000022b0a00 x19: ffff00000309b580 x18: 3030387830383231 x17: 0048008800d90326 x16: 0324032303260320 x15: ffff80000a11b780 x14: ffff80000a11b830 x13: ffff80000a11b834 x12: ffff00003fd90740 x11: ffff00000391da00 x10: 00000000000007d0 x9 : ffff80000a11b6b0 x8 : ffff00000391e230 x7 : 0000000000000000 x6 : ffff00000391da00 x5 : 000000001dcd6500 x4 : 0000000000000000 x3 : ffff00000309b5d0 x2 : ffff00000391da00 x1 : 0000000000000000 x0 : ffff800008fdd010 Call trace: pwm_imx_tpm_apply+0x12c/0x3f0 pwm_apply_state+0x5c/0xbc pwm_backlight_update_status+0xc4/0x1ac drm_panel_enable+0x70/0xe0 [...] Fix this by remembering the suspend state and returning -EAGAIN in HW related functions (pwm_imx_tpm_apply() and pwm_imx_tpm_get_state()) as long as pwm_imx_tpm_resume() has not been called. Signed-off-by: Lothar Waßmann --- V2: one hunk was missing in the first mail --- drivers/pwm/pwm-imx-tpm.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c index e5e7b7c339a8..537c7182f988 100644 --- a/drivers/pwm/pwm-imx-tpm.c +++ b/drivers/pwm/pwm-imx-tpm.c @@ -64,6 +64,7 @@ struct imx_tpm_pwm_chip { u32 user_count; u32 enable_count; u32 real_period; + int suspended; }; struct imx_tpm_pwm_param { @@ -140,6 +141,9 @@ static void pwm_imx_tpm_get_state(struct pwm_chip *chip, u32 rate, val, prescale; u64 tmp; + if (tpm->suspended) + return -EAGAIN; + /* get period */ state->period = tpm->real_period; @@ -294,6 +298,9 @@ static int pwm_imx_tpm_apply(struct pwm_chip *chip, struct pwm_state real_state; int ret; + if (tpm->suspended) + return -EAGAIN; + ret = pwm_imx_tpm_round_state(chip, ¶m, &real_state, state); if (ret) return ret; @@ -397,6 +404,7 @@ static int __maybe_unused pwm_imx_tpm_suspend(struct device *dev) if (tpm->enable_count > 0) return -EBUSY; + tpm->suspended = 1; clk_disable_unprepare(tpm->clk); return 0; @@ -411,6 +419,7 @@ static int __maybe_unused pwm_imx_tpm_resume(struct device *dev) if (ret) dev_err(dev, "failed to prepare or enable clock: %d\n", ret); + tpm->suspended = 0; return ret; } -- 2.30.2